1. Field of the Invention
This invention relates to devices for cutting stone accurately to shape, and more particularly for cutting imitation stone at a building construction site for use in bathroom and kitchen counters, floors, walls, fireplaces, patios, cobblestone walkways, and for a variety of other applications.
2. Description of Related Art
Natural stone is a highly desired construction material, but its use entails high labor and shipping costs. Imitation stone, also known as manufactured stone, has been used for over thirty years and is commonly substituted for natural stone because of its low shipping and installation cost, high quality, and low weight. Imitation stone is made from poured concrete, pumice, and special high-quality, long-lasting permanent pigments. Imitation stone is typically adhered to a wall surface with a cement stucco mixture that is often very rich in Portland cement; in contrast, natural stones are set on top of one another. It is usually necessary to trim and shape imitation stones preparatory to their installation in a wall or other setting.
Prior to my invention, there existed no satisfactory cutting device for imitation stone. Stone and tile cutting devices that require a percussive blow were disclosed in U.S. Pat. No. 3,886,927 to Chattin and U.S. Pat. No. 812,973 to Barr et al., respectively, but a percussive blow risks shattering imitation stone. U.S. Pat. No. 600,856 to Brinkman disclosed a tile cutting machine that used a movable upper and a fixed lower blade aligned in a cutting plane, each blade having serrated teeth, wherein the upper blade was movable between a pair of upright standards and actuated by means of toggles by movement of a hand lever. I have found, however, that one obtains a more precise and even cut of imitation stone if the upper and lower blades each have a smooth edge instead of a serrated edge, and if the edges are asymmetrical in vertical cross-section and are oppositely canted with respect to the cutting plane, as explained below. U.S. Pat. No. 2,053,043 to Patterson disclosed a stone cutting machine that employed a crank disk to actuate movement of an upper blade by means of toggles; the cutting edges of the upper and lower blade were V-shaped—that is, each blade edge was symmetrical in vertical cross-section. U.S. Pat. No. 6,079,304 to Bisceglia disclosed a pinch blade tool, intended for trimming shingles, having a stationary blade and a movable blade that moved with a sliding action to pinch work between the blades, but did not teach the use of asymmetrical blade edges.
My cutter employs a single pair of apposed cam surfaces for imparting, by downward movement of a handle, a gradual and uniform downward cutting motion to an upper blade thereof. U.S. Pat. No. 1,805,163 to Buckner disclosed a belt cutter that had two, laterally spaced-apart pairs of apposed cam surfaces, linked for unitary motion by a connecting link, for moving an upper, cutting blade downward through a work piece (belt). U.S. Pat. No. 2,626,664 to Regele also employed a dual cam drive in combination with an upper blade that was inclined with respect to the lower blade; the upper blade simultaneously descended and swung lengthwise the lower blade to achieve a progressive cut. Dual cam drives, such as those of Buckner and Regele, are unnecessarily complex and expensive for an imitation stone cutter. A single cam drive in combination with my improved blade edges provides a simpler, less expensive and more robust cutter.